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81.
H. E. Marsh JR. 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):1397-1418
Abstract The complex and important role of the propellant binder in solid-propellant rockets is described. The severe weight problems of space exploratrion cause high propellant performance to be of major concern in a highly competitive field. Binders contribute to performance, not only in terms of fuel value, but by being compatible with energetic components and by providing good mechanical properties. Both sterilization required for planetary landings and compatibility problems of new energetic oxidizers generate new requirements too stringent for existing binders; only binders composed essentially of saturated aliphatic hydrocarbon are predicted to be suitable. Several saturated-binder developments are in progress. The achievements of one of these programs, based on free-radical synthesis, are evaluated against the goals of the new binder. 相似文献
82.
G.W. SWENSON JR 《Journal of sound and vibration》2002,255(3):519-529
A directional microphone system for field recording of sounds in the air often involves a parabolic reflector to focus the sound waves on the microphone (transducer) element. Some deficiencies of such a system are noted with respect to reproduction of spectra. The reflector system, involving as it does a structure comparable to a wavelength in linear dimension, is not susceptible to traditional high- or low-frequency approximate methods of computation. Modern numerical techniques now permit precise calculation of the directional responses of small reflectors of various shapes. One result is a proposal for a very economical and effective system involving a plane reflector. Other baffle shapes are also investigated, which may be of interest in special applications. 相似文献
83.
Matej Kanduč Alexander Schlaich Emanuel Schneck Roland R. Netz 《Advances in colloid and interface science》2014
A review of various computer simulation approaches for the study of the hydration repulsion between lipid membranes and polar surfaces is presented. We discuss different methods and compare their advantages and limitations. We consider interaction pressures, interaction thermodynamics, and interaction mechanisms. We take a close look at the influence of the experimental boundary conditions and at repulsion mechanisms due to the unfavorable overlap of interfacial water layers. To this end, we analyze several distinct water order parameters in simulations of interacting polar surfaces and compare the results to the predictions of simple continuum theories. 相似文献
84.
Roman Schowner Iris Elser Mathis Benedikter Mohasin Momin Wolfgang Frey Tanja Schneck Laura Sthr Michael R. Buchmeiser 《Angewandte Chemie (International ed. in English)》2020,59(2):951-958
The origin of hydroxyl group tolerance in neutral and especially cationic molybdenum imido alkylidene N‐heterocyclic carbene (NHC) complexes has been investigated. A wide range of catalysts was prepared and tested. Most cationic complexes can be handled in air without difficulty and display an unprecedented stability towards water and alcohols. NHC complexes were successfully used with substrates containing the hydroxyl functionality in acyclic diene metathesis polymerization, homo‐, cross and ring‐opening cross metathesis reactions. The catalysts remain active even in 2‐PrOH and are applicable in ring‐opening metathesis polymerization and alkene homometathesis using alcohols as solvent. The use of weakly basic bidentate, hemilabile anionic ligands such as triflate or pentafluorobenzoate and weakly basic aromatic imido ligands in combination with a sterically demanding 1,3‐dimesitylimidazol‐2‐ylidene NHC ligand was found essential for reactive and yet robust catalysts. 相似文献
85.
A new and unsual transition is reported in Ba2NaNb5O15: the crystal, which was previously known to undergo at 573 K a ferroelastic transition 4mm → mm2 (C4v → C2v), reverts back at 110 ± 5 K to a low temperature phase of 4mm (C4v) symmetry. Thus this crystal presents a unique example of a ferroelastic (mm2) phase stable in a wide temperature range (470 K) and sandwiched between two phases possessing the same higher point symmetry. 相似文献
86.
Aitala EM Amato S Anjos JC Appel JA Ashery D Banerjee S Bediaga I Blaylock G Bracker SB Burchat PR Burnstein RA Carter T Carvalho HS Costa I Cremaldi LM Darling C Denisenko K Fernandez A Gagnon P Gerzon S Gobel C Gounder K Granite D Halling AM Herrera G Hurvits G James C Kasper PA Kondakis N Kwan S Langs DC Leslie J Lichtenstadt J Lundberg B Manacero A MayTal-Beck S Meadows B de Mello Neto JR Milburn RH de Miranda JM Napier A Nguyen A d'Oliveira AB O'Shaughnessy K Peng KC Perera LP Purohit MV 《Physical review letters》1996,76(3):364-367
87.
G. Buogo G. Nadai A. Kern R. Scarpitti B. Rossi Mario Pittarelli M. F. Bengen E. Bohm Klostermann Schneck Cl. Zäch M. Paget Génel C. C. Proutv G. H. Wray G. P. Sanders E. B. Meigs N. R. Blatherwick C. A. Cary B. G. Hartmann F. Hillig W. Mohr W. Müller R. Barfuß-Knochendöppel Norabelle D. Weathers M. Fouassier W. Leithe G. Schwarz Edith Müller J. Tillmans R. Strohecker H. Hostettler S. Tanaka M. Endo H. Halstensen L. W. Brown W. V. Price G. Stamm J. Umbrecht Franz Maier F. E. Nottbohm O. Baumanna M. Siegfeld J. Pier O. Baumann J. Pien S. Herschdoerfer R. H. Shaw 《Analytical and bioanalytical chemistry》1934,99(11-12):439-452
88.
The influence of CO adsorption on the ordinary Hall coefficient, RHO, the extraordinary Hall coefficient, RHE, the perpendicular magnetoresistivity ΔRmag O and the saturation magnetization, BS, of Ni films with thicknesses between 1 and 200 nm has been studies as a function of the CO coverage at 77 and 273 K. There is a maximum in ΔRHE at a coverage of about half a monolayer. ΔRHO, ΔΔRmag O and ΔBS exhibit an oscillating behaviour. 相似文献
89.
90.
M. Schiekel F. Scheibe U. Schneck T. Lemmen 《Journal of Radioanalytical and Nuclear Chemistry》1993,174(2):199-204
Chloride ions may be removed from reinforced concrete using an electroosmotic procedure. Process controlling requires a nondestructive analyzing method. For this purposes activation analysis with both thermal and fast neutrons has been investigated using low flux neutron sources. Results are compared and discussed for in-situ chloride determination.Presented at the MTAA-8 Conference, September 16–20, 1991, Vienna, Austria. 相似文献